Nonuniform states in noncentrosymmetric superconductors

TL;DR

This paper explores how nonuniform superconducting states can naturally occur in noncentrosymmetric crystals due to Lifshitz invariants, deriving these from microscopic theory.

Contribution

It provides a microscopic derivation of Lifshitz invariants responsible for nonuniform states in noncentrosymmetric superconductors.

Findings

Nonuniform states can exist without external magnetic fields.

Lifshitz invariants are key to understanding these states.

Derivation from microscopic theory confirms their fundamental role.

Abstract

In noncentrosymmetric crystals, nonuniform superconducting states are possible even in the absence of any external magnetic field. The origin of these states can be traced to the Lifshitz invariants in the free energy, which are linear in spatial gradients. We show how various types of the Lifshitz invariants in noncentrosymmetric superconductors can be derived from microscopic theory.